Method and composition to inhibit symptoms of allergy

ABSTRACT

Fluorenone and anthraquinone compounds substituted by at least one tetrazolyl group in one ring, and further substituted in the other ring, optionally for the fluorenones, have antiallergic activity.

This is a division of application Ser. No. 394,423, filed on Sept. 5,1973 now U.S. Pat. No. 3,939,173.

The invention relates to tricyclic compounds having medicinalproperties, the synthesis of the compounds and their adaptation formedicinal use.

It has been found that tricyclic compounds of formula I definedhereinbelow are active in mammals and in in vitro mammalian preparationsas inhibitors of allergic reactions associated with reaginic antibodiesof the kind responsible for asthma in man, and that this effect isattributable to the suppression of the release of anaphylacticmediators.

In formula I ##STR1## at least one of Z¹ and Z² is a 5-(1-R)tetrazolylor a 5-(2-R)tetrazolyl group wherein R is hydrogen or alkyl having 1 to6 carbon atoms, and the other is selected from carboxy,5-(1-R)tetrazolyl and 5-(2-R)tetrazolyl as defined;

Z³ represents a bond or is carbonyl; and when Z³ represents a bond,

Z² is also selected from hydrogen, nitro, cyano, halogen preferablychlorine or bromine, alkylsulphinyl, alkylsulphonyl, acyl, alkyl oralkoxy wherein the "alkyl" moiety of each of the acyl, alkyl, alkoxy,alkylsulphinyl, and alkylsulphonyl groups has 1 to 6 carbon atoms;

Together with salts, and where one of Z¹ or Z² is carboxyl, amides andesters of said compounds.

Compounds of formula I include 2-Z¹, 7-Z² -fluorenones, and 2-Z¹, 6-Z²-anthraquinones in which compounds at least one of Z¹ and Z² is5-tetrazolyl and the other is selected from 5-tetrazolyl and carboxy,together with salts of said compounds.

Esters of compounds of formula I include alkyl esters having 1 to 6carbon atoms, and amides include N-alkyl- and N,N-dialkylamides whereinthe alkyl groups have 1 to 6 carbon atoms.

The inhibition activity of the compounds of formula I has beendemonstrated (a) in tests using the response of passive cutaneousanaphylaxis (PCA test) in which is measured the skin reaction producedas the result of interaction between specific antigen injectedintravenously and cell-fixed reaginic antibody previously injected intothe skin of a mammal (see for example Z. Ovary: Fedn, Proc. Am. Soc.exp. Biol. 24, 94 (1965)), (b) by measurement of the amount of histaminereleased after antigen challenge of peritoneal mast cells from activelysensitised rats (see for example, 1. Acta Pharmacol. et Toxicol. 30,supp. 1 (1971), 2. Thorax, 27/1, 38 (1972), and (c), by measurement ofthe histamine released from human chopped lung tissue passivelysensitised in vitro with reaginic antibody when challenged with thehomologous antigen (Br. Med. J. 3,272 (1968)). The activity of acids offormula I has been demonstrated as described hereinabove using solutionsof the carboxylate anion.

For the sake of convenience, compounds of formula I wherein either ofZ.sup. 1 and Z.sup. 2 is an alkyl carboxylate group, shall hereinafterbe referred to as `esters` of formula I. Similarly references to`amides` of formula I shall be construed as references to compounds offormula I wherein one of Z.sup. 1 and Z.sup. 2 is an optionallysubstituted carboxamide, and references to `salts` of formula I shallmean compounds of formula I wherein one or both of Z.sup. 1 and Z.sup. 2is a carboxylate or tetrazolyl salt group.

Pharmaceutically acceptable salts of formula I include ammonium salts,alkali metal salts such as sodium and potassium salts, alkaline earthsalts such as magnesium and calcium salts, and salts of organic bases,for example, amine salts such as triethanolamine anddiethylaminoethylamine salts, and piperazine and morpholine salts.Especially valuable are water soluble salts of formula I most preferablythose having a solubility in water of at lest 1 mg/ml.

The anti-allergic activity of the salts of formula I lies in the anionand the nature of the cation does not contribute to the activity, butfor medicinal purposes the cation must of course be pharmaceuticallyacceptable.

Pharmaceutically acceptable cations in compounds of formula I includehydrogen, ammonium, alkali metal cations such as sodium and potassium,alkaline earth metal cations such as calcium and magnesium and organicbase cations, for example, alkylammonium cations of such alkylamines astriethanolamine and diethylaminoethylamine, piperazinium andmorpholinium cations.

Suitable substituted carboxamide groups include N-alkyl and N,N-dialkylsubstituted carboxamide groups wherein the alkyl moiety is an alkylgroup having 1 to 6 carbon atoms, preferably 1 to 4 carbon atoms.

Preparation of compounds of formula I may be effected by any methodknown in the art of preparing them and compounds of analogous chemicalstructure. In general the compounds of formula I wherein one of Z.sup. 1and Z.sup. 2 is a carboxylate derivative (for example an amide, ester orsalt), are prepared by suitable treatment of the corresponding acid.However, in certain circumstances it is possible to prepare suchderivatives without prior isolation of the carboxylic acid, either bythe choice of suitable reactants or by forming the desired derivative ina reaction mixture of the acid, without first isolating the acid.

Methods for the preparation of compounds and salts of formula I aredescribed hereinbelow, but it will be understood that in some instancesthe methods may be adopted to yield the corresponding esters or amidesof formula I

1. Hydrolysis of a compound of formula II ##STR2## Wherein one of Y.sup.1 and Y.sup. 2 is a carboxyl group precursor, such as a nitrile group,trichloromethyl group or a group COL.sup. 1 wherein L.sup. 1 is aleaving group, such as a nucleophilic atom or group, for example, atrichloromethyl group, an optionally substituted amino group, a halogenatom or an alkoxy group; and the other of Y.sup. 1 and Y.sup. 2 is thegroup Z¹ or Z.sup. 2, as appropriate, as defined in formula I; andZ.sup. 3 has the meaning defined in formula I. Hydrolysis isconveniently effected by heating a compound of formula II with a diluteaqueous alkali, or with a dilute aqueous one may use dilute sulpuricacid, dilute hydrochloric acid with acetic acid, or dilute aqueoussodium hydroxide solution. Hydrolysis with aqueous alkali will yieldinter alia an aqueous solution of a dicarboxylate salt but if it isdesired to collect the maximum amount of carboxylic acid, then thereaction mixture should be acidified when hydrolysis is completed toprecipitate the acid. On the other hand if the desired end-product isthe carboxylate salt, then following hydrolysis, the cation of thedesired salt may be added to precipitate the desired salt by the commonion effect without prior isolation of the corresponding acid.

By means of nucleophilic substitution reactions analogous to hydrolysis,for example, alcoholysis and ammonolysis, compounds of formula I otherthan the carboxylic acid may be prepared directly from compounds offormula II. Thus reaction of a compound of formula II with anappropriate alcohol yields an ester of formula I, and reaction withammonia or an appropriate primary or secondary amine yields an amide offormula I.

2. Cyclisation of a compound of formula III ##STR3## wherein Z.sup. 1,Z.sup. 2 and Z³ have the meaning defined in formula I and Q is ahydroxyl, alkoxy or an optionally substituted amino group, a halogenatom, or a RCO.sub. 2 group, a ROCO.sub. 2 group or a RSO₃ group whereinR is alkyl or aryl. Cyclisation may be effected by heating a compound offormula III at an elevated temperature, for example up to about 300° C.Preferably heating is carried out in the presence of a Lewis acid underanhydrous conditions or a protonic acid, optionally in the presence of anon-polar solvent. Preferred Lewis acids include boron trifluoride andaluminium trichloride and preferred protonic acids include sulphuric,hydrochloric and polyphosphoric acids. If, however, Z.sup. 2 is acarboxylate substituent in the 5-position of the nascent compound offormula I, reaction conditions and/or the group Q must be chosen so asto avoid reaction of the group Z.sup. 2.

In the case of anthraquinone compounds of formula I cyclisation to formthe carbonyl linkage in the tricyclic nucleus may be effected to formeither of the two carbonyl linkages of the tricyclic anthraquinonenucleus.

3. Oxidation of a compound of forumula VIII ##STR4## wherein one ofW.sup. 1 and W.sup. 2 is a lower alkyl group or a group C(:O)R wherein Ris an optionally substituted lower alkyl group having 1 to 4 carbonatoms, or is OH, and the other of W.sup. 1 and W.sup. 2 is Z.sup. 1 orZ.sup. 2, as appropriate, as defined in formula I; and Z.sup. 3 is asdefined in formula I. Oxidation of compounds wherein W.sup. 1 and/orW.sup. 2 are lower alkyl groups may be effected with such conventionaloxidising agents as acid or alkaline aqueous potassium permanganatesolution; chromium trioxide, for example, with acetic acid or sulphuricacid; oxygen in the presence of a conventional catalyst such as lead,cobalt and manganese salts, for example, lead acetate; or aqueoussolutions of sodium dichromate.

Oxidation of compounds wherein W.sup. 1 or W.sup. 2 are the groupsC(:O)R may be effected with such conventional oxidising agents aschromium trioxide, for example, with acetic acid or sulphuric acid;aqueous solutions of salts of hypochlorous and hypobromous acids in thepresence of a base; sodium or potassium dichromate with acetic acid; ornitric acid. These oxidation procedures are advantageously effected withheating in the liquid phase.

4. Oxidation of a compound of formula IX ##STR5## wherein Z.sup. 1 andZ.sup. 2 have the meaning defined hereinbefore in formula I, Y.sup. 3 isa group Z.sup. 3 as defined hereinbefore in formula I and Y.sup. 4 is amethylene group; or Y.sup. 4 and Y.sup. 3 are the same or different andare each selected from CH and CR wherein R is lower alkyl. Oxidation ofcompounds of formula IX may be effected with such conventional oxidisingagents as nitric acid, aqueous solutions of hypochlorous and hypobromousacids in the presence of base; chromium trioxide, for example withacetic acid or with sulphuric acid; or aqueous solutions of sodiumdichromate.

Oxidation of compounds of formula IX wherein Y.sup. 4 is a methylenegroup and Y.sup. 3 is a bond, or Y.sup. 4 and Y.sup. 3 are each CH, mayalso be effected with such conventional oxidising agents as oxygen inthe presence of triton B in pyridine solution; or oxygen in the presenceof potassium t-butoxide in the presence of t-butanol anddimethylsulphoxide.

Compounds analogous to the compounds of formula IX wherein either ofZ.sup. 1 and Z.sup. 2 is replaced by a group W.sup. 1 or W.sup. 2, asappropriate, as defined in formula VIII, may also be oxidised so as toproduce carboxylic acids or salts of formula I. Oxidation in the case ofsuch compounds may be effected with such conventional oxidising agentsas chromium trioxide, for example, with acetic acid or with sulphuricacid; or aqueous solutions of sodium dichromate. In the case of suchcompounds wherein neither of W.sup. 1 and W.sup. 2 is alkyl, oxidationmay also be effected with such conventional oxidising agents as aqueoussolutions of salts of hypobromous or hypochlorous acids in the presenceof a base; or nitric acid. Advantageously any of the hereinbeforedescribed oxidation procedures wherein aqueous solutions of sodiumdichromate are employed, are carried out at an elevated temperature in asealed container. Oxidation of the groups W.sup. 1 and W.sup. 2 in sucha case is preferably effected at a temperature of from 200° to 210° C.Oxidation of the tricyclic anthracene; 9,10-dialkyl anthracene oranthrone nucleus in such a case is desirably effected at a temperatureof from 250° to 260° C.

The compounds of formula I may also be prepared by formation of a5-tetrazolyl group as the final step. Thus in formula I wherein one orboth of Z.sup. 1 and Z.sup. 2 are tetrazolyl or (1-alkyl)tetrazolylgroups, these compounds may be prepared by reaction of hydrazoic acid ora salt thereof or nitrous acid with an appropriate compound of formulaXIV wherein ##STR6## Y.sup. 7 is a group Z.sup. 1 as defined in formulaI or a tetrazolyl group precursor and Y.sup. 8 is a group Z.sup. 2 asdefined in formula (I) or a tetrazolyl group precursor, provided that atleast one of Y.sup. 7 and Y.sup. 8 is a tetrazolyl group precursor.

When hydrazoic acid or a salt thereof is used, a suitable tetrazolylgroup precursor is a group ##STR7## wherein R.sup. 3 and R.sup. 4together form a bond (nitrile), R.sup. 3 is hydrogen or alkyl and R.sup.4 is alkoxy having 1 to 6 carbon atoms (imidoester), thioalkyl having 1to 6 carbon atoms (imidothioester), --NH--NH.sub. 2 (amidrazone), oramino (amidine) or R.sup. 3 is hydroxy and R.sup. 4 is amino(amidoxime), or R.sup. 3 is alkyl and R.sup. 4 is halogen (imidohalide).In the case of amidoximes and nitriles, only tetrazolyl compounds may beproduced and in the case of imidohalides only alkyltetrazolyl compoundsmay be produced. The reaction is preferably carried out in a polaraprotic liquid medium using a salt of hydrazoic acid.

When nitrous acid is used, a suitable tetrazolyl precursor group is agroup ##STR8## Wherein R.sup. 3 is hydrogen or alkyl and R.sup. 4 is--NH--NH (amidrazone) or R.sup. 3 is hydrogen and R.sup. 4 is amino(amidine). In the latter case, reduction of the intermediate nitrosationproduct, with or without prior isolation, using for example sodiumamalgam, is required to give the corresponding tetrazolyl compound.

The tetrazolyl compounds of formula I thus prepared may be isolated asthe free acid or as a tetrazolyl salt, and the one converted to theother in known manner and as specifically described below in relation tothe carboxylic acids of formula I and their salts.

The 5-(1- and 2- alkyl)tetrazolyl compounds of formula I may be madefrom the corresponding tetrazolyl compounds of formula I or their saltsby alkylation.

Salts of formula I may be isolated from a reaction medium by anyconventional process for the isolation of salts from a solution thereofin a polar medium.

Desirably the salts of formula I are purified prior to incorporation ina pharmaceutical composition by any conventional method.

Esters and amides of acids of formula I may be prepared by anyconventional method including esterification of the acid or acidchloride with an alkyl or aryl alcohol to yield the corresponding alkylor aryl ester respectively and reaction of the acid or acid chloridewith ammonia or an amine to yield the corresponding amide or substitutedamide respectively. Compounds of formula I where Z.sup. 1 and Z.sup. 2are different and are chosen from acid, ester, amide and salt functions,may be prepared by the above methods, and by partial hydrolysis, whereappropriate.

The compounds of formula I are useful in the treatment or prophylaxis ofmammalian allergic conditions such as asthma and other allergic chestconditions, hay fever (allergic rhinitis), conjunctivitis, urticaria andeczema. In particular they are of value in reaginic mediated Type Ihypersensitivity asthma (`extrinsic asthma`) and the so-called`intrinsic asthma` in which no sensitivity to extrinsic antigen can beshown.

The magnitude of a prophylactic or therapeutic dose of compound offormula I will of course vary with the nature of the severity of theallergic condition to be treated and with the particular compound offormula I and its route of administration. In general the dose rangelies within the range of 2 μg. to 100 mg. per Kg. body weight of amammal.

In the case of an allergic condition as defined hereinbefore, forexample, allergic asthma, a suitable dosage is from 20 μg. to 0.5 mg.,for example about 0.1 to 0.5 mg., of a compound of formula I, per Kg. ofbodyweight of the patient undergoing treatment, when pulmonaryadministration as described hereinafter is employed. In the case where acomposition for intravenous administration is employed a suitable dosagerange is from 0.2 to 10 mg. (preferably 1 to 5 mg.) of a compound offormula I per Kg. of bodyweight of patient, and in the case where anoral composition is employed a suitable dosage range is from 1 to 50 mg.of a compound of formula I per Kg. of bodyweight of a patient,preferably from 10 to 40 mg/Kg.

In the case where a composition for nasal and ocular administration isemployed, for example, in the treatment of allergic rhinitis, a suitabledose is from 0.5 to 25 mg. of a compound of formula I per patient.

The pharmaceutical compositions of the present invention comprise acompound of formula I as an active ingredient, and may also containpharmaceutically acceptable carrier and optionally other therapeuticingredients. The compositions include compositions suitable for oral,rectal, opthalmic, pulmonary, nasal, dermal, topical, or parenteral(including subcutaneous, intramuscular and intravenous) administration,although the most suitable route in any given case will depend on thenature and severity of the condition being treated, and on the nature ofthe active ingredient. They may be conveniently presented in unit dosageform and prepared by any of the methods well known in the art ofpharmacy.

Pharmaceutical compositions of the present invention suitable for oraladministration may be presented as discrete units such as capsules,cachets or tablets each containing a predetermined amount of the activeingredient; as a solution or a suspension in an aqueous liquid, anon-aqueous liquid, an oil-in-water emulsion or a water-in-oil liquidemulsion. Such compositions may be prepared by any of the methods ofpharmacy but all methods include the step of bringing into associationthe active ingredient with the carrier which constitutes one or moreaccessory ingredients.

Desirably, each discrete unit contains from 50 mg. to 500 mg. of theactive ingredient.

A valuable form of a pharmaceutical composition of the presentinvention, for use in the treatment of allergic asthma, is one suitablefor pulmonary administration via the buccal cavity. Preferably thecomposition is such that particles having a diameter of 0.5 to 7μ, mostpreferably 1 to 6μ, containing active ingredient, are delivered intolungs of a patient. Such compositions are conveniently in the form ofdry powders for administration from a powder inhalation device orself-propelling powder-dispensing containers; preferably the powderscomprise particles containing active ingredient of which particles atleast 98% by weight have a diameter greater than 0.5μ and at least 95%by number have a diameter less than 7μ. Most desirably at least 95% byweight of the particles have a diameter greater than 1μ and at least 90%by number of the particles have a diameter less than 6μ.

The compositions in the form of dry powders preferably include a solidfine powder diluent and are conveniently presented in a pierceablecapsule, for example of gelatin.

Self-propelling compositions of the invention may be eitherpowder-dispensing compositions or compositions dispensing the activeingredient in the form of droplets of a solution or suspension.Self-propelling powder-dispensing compositions include a liquidpropellant having a boiling point of below 65° F at atmosphericpressure. Generally the propellant may constitute 50 to 99.9% w/w of thecomposition whilst the active ingredient may constitute 0.1 to 20% w/w,for example, about 2% w/w, of the composition. The carrier in suchcompositions may include other constituents, in particular a liquidnon-ionic or solid anionic surfactant, or a solid diluent (preferablyhaving a particle size of the same order as of the particles of activeingredient) or both. The surfactant may constitute up to 20% w/w, thoughpreferably it constitutes below 1% w/w of the composition.

Self-propelling composition wherein the active ingredient is present insolution comprise an active ingredient, propellant and co-solvent, andadvantageously an antioxidant stabiliser. The co-solvents may constitute5 to 40% w/w of the composition, though preferably less than 20% w/w ofthe composition.

Compositions of the present invention may also be in the form of aqueousor dilute alcoholic solution, optionally a sterile solution, of theactive ingredient for use in a nebuliser or atomiser.

Compositions of the present invention suitable for parenteraladministration conveniently comprise sterile aqueous solutions of theactive ingredient, which solutions are preferably isotonic with blood ofa patient under treatment.

Pharmaceutical composition of the present invention suitable for topicaluse include compositions suitable for administration to the skin, eyes,nose and mouth. Compositions for use on the skin include lotions andcreams comprising liquid or semi-solid emulsions, either oil-in-water orwater-in-oil, and ointment, preferably containing from 0.2 to 5% w/v ofthe active ingredient. Desirably the creams and ointments should containa preservative such as methyl hydroxybenzoate.

Compositions for administration to the eye include eye drops comprisingthe active ingredient in aqueous or oily solution and ointments,preferably containing 0.2 to 5% w/v of the active ingredient. The eyedrops are desirably fungistatic and bacteriostatic and are preferablyprepared sterile.

Compositions suitable for administration to the nose include powder,self-propelling and spray compositions similar to those alreadydescribed under compositions suitable for pulmonary administration buthaving when dispersed, a somewhat larger particle size of the order of10 to 200 microns. Other compositions suitable for nasal administrationinclude a coarse powder having a particle size of 20 to 500 micronswhich is administered in the manner in which snuff is taken i.e. byrapid inhalation through the nasal passage from a container of thepowder held close up to the nose. Another composition suitable for nasaladministration is nasal drops comprising 0.2 to 5% w/v of the activeingredient in aqueous or oily solution.

Compositions suitable for topical administration in the mouth includelozenges comprising 10 to 100 mg. of the active ingredient in aflavoured base, usually sucrose and acacia or tragacanth; and pastillescomprising 10 to 100 mg. of the active ingredient in an inert base suchas gelatin and glycerin; or sucrose and acacia.

Other therapeutic ingredients suitable for inclusion in the hereinbeforedescribed compositions, especially in the case of those compositionsintended for use in the treatment of allergic asthma, includebronchodilators such as isoprenaline, adrenaline, orciprenaline,isoethanine and physiologically acceptable acid addition salts thereof,especially isoprenaline sulphate. Conveniently the bronchodilator ispresent in an amount of 0.1 to 50% w/w of the weight of activeingredient present.

Included within the scope of the present invention, but in no waylimited thereto, are the following specific features:

1. A compound of formula I as defined hereinabove, where novel.

2. The synthesis of compounds of formula I as defined hereinabove, byany method known in the art for preparing them and compounds ofanalogous chemical structure.

3. Pharmaceutical compositions comprising a compound of formula I asdefined hereinabove in association with a pharmaceutically acceptablecarrier therefor.

4. The preparation of pharmaceutical compositions comprising a compoundof formula I as defined hereinabove as an active ingredient, by anyconventional method, including admixture of the ingredients.

5. A method of treatment or prophylaxis of mammalian allergic conditionscomprising administration of a therapeutic or prophylactic doserespectively, of a compound of formula I as defined hereinabove.

Set forth below are examples of this invention.

EXAMPLE 1 2,6-Di-(5-tetrazolyl)anthraquinone

a. Anthraquinone-2,6-dicarboxamide

Anthraquinone-2,6-dicarboxylic acid (5.0g.) was boiled with thionylchloride (50 ml.) and dimethylformamide (0.25 ml.) for 45 min. Theresulting clear solution was evaporated to dryness and the residual acidchloride treated with 0.880 ammonia. After standing for 30 min, thecrude amide was filtered off, washed with water and dried, m.pt. 420°(decomp.).

b. 2,6-Dicyanoanthraquinone

Thionyl chloride (10.0 ml) was added to dimethylformamide (100 ml.) at-30° C. with stirring in 1 ml. portions. To the resulting solution,anthraquinone-2,6-dicarboxamide (4.74g.) was added in one portion andthe temperature of the mixture was allowed to rise slowly to 5° C. byplacing in an ice-bath. After 30 min. at this temperature, the mixturewas heated over 30 min. to 65° C. The heterogeneous mixture was thenpoured into iced water and the solid filtered off, dried, andrecrystallised from deimethylsulphoxide, 2.60g. m.p. 392° C. (decomp.)in a sealed, evacuated tube.

c. 2,6-Di-(5-tetrazolyl)anthraquinone

2,6-Dicyanoanthraquinone (2.06g.), sodium azide (1.30g.), ammoniumchloride (1.07g.) and dimethylformamide (100 ml.) were stirred togetherat 105°-110° C. for 24 hr. The mixture was poured into an excess ofdilute hydrochloric acid, and the solid product filtered off and washedwith water. The solid was treated with 21/2% potassium bicarbonatesolution (100 ml.) and some in-insoluble material was filtered off. Thefiltrate was acidified with dilute hydrochloric acid, heated to boilingto coagulate the gelatinous precipitate, and the crude product filteredoff, dried, and recrystallised from dimethylformamide, decomposes atabout 300° C.

EXAMPLE 2

5-(7-Propoxycarbonyl-2-fluorenone)tetrazole

a. Dipropyl fluorenone-2,7-dicarboxylate (m.p. 146.5° to 148° C.) wasprepared from fluorenone-2,7-dicarboxylic acid by esterification withpropanol in the presence of sulphuric acid. This diester was hydrolysedto the 7-propoxycarbonylfluorenone-2-carboxylic acid (m.p. 250°-252° C.)using sodium hydroxide in the presence of propanol. This half-ester wastreated with thionyl chloride to provide the corresponding acidchloride, and the latter converted to the corresponding amide (m.p.278° - 279° C) by treatment with aqueous ammonia.

b. 7-Propoxycarbonylfluorenone-2-carboxamide (3.8g.) was dissolved indimethylformamide (50 ml.) wth warming and the solution was then stirredand cooled to -25° C. Thionyl chloride (7.55 ml) was added dropwise over10 minutes and the mixture was allowed to warm to 0° C., left at thistemperature for 60 hours, and then treated with an ice water mixture.The pale yellow solid was filtered, washed with water and dried in vacuoto give 7-propoxycarbonylfluorenone-2-carbonitrile, m. pt. 198°-199° C.

c. A portion (2g.) of this nitrile, sodium azide (450 mg.) and ammoniumchloride (400 mg.) in dimethylformamide (20 ml.) were heated to 100° C.,with stirring, for 18 hours. The mixture was cooled, poured into water(200 ml.) and made just acid with 2N hydrochloric acid. The gelatinousprecipitate was filtered, washed with water, and redissolved in aqueoussodium bicarbonate; the solution was filtered and then acidified with 2Nhydrochloric acid. The resulting solid was filtered, dissolved in 2Naqueous ammonia, reprecipitated with hydrochloric acid and thenfiltered, washed with water and dried in vacuo to give5-(7-propoxycarbonyl-2-fluorenone)tetrazole, m.pt. 227°-228° C.(decomp.)

EXAMPLE 3 Preparation of 2,7-Di(5-tetrazolyl)fluorenone

A. Preparation of 2,7-Dicyanofluorenone

A mixture of 2,7-dibromofluorenone (14.92 g) and cuprous cyanide (9.35g) in dimethylformamide (40 ml) was heated to reflux for 5 hours. Thehot mixture was added to a solution of ferric chloride (38 g) in water(57 ml) and concentrated hydrochloric acid (9.5 ml). The mixture washeated on a steam bath for 2 hours, filtered, treated again with asimilar aqueous acidic solution of ferric chloride and then filtered,washed well with water and dried in vacuo to give 2,7-dicyanofluorenoneas a yellow solid m.p. above 300° C.

B. Preparation of 2,7-Di(5-tetrazolyl)fluorenone

A mixture of 2,7-dicyanofluorenone (4.6 g) sodium azide (2.62 g) andammonium chloride (2.6 g) in dimethylformamide (25 ml) was stirred andheated to 100° C for 10 hours. The mixture was cooled, treated with anexcess of 2N hydrochloric acid and the solid was filtered, washed withwater, dried in vacuo and recrystallised from a mixture ofdimethylformamide and water. This product was dissolved in an excess of0.1N aqueous sodium hydroxide, the solution was filtered and acidifiedwith hydrochloric acid. The resulting precipitate was filtered, washedwith water and dried in vacuo to give 2,7-di-(5-tetrazolyl)fluorenone,m.p. above 300° C.

EXAMPLE 4 5-(7-Butylfluorenone-2)-tetrazole

A mixture of 7-butylfluorenone-2-carboxylic acid (800 mg), thionylchloride (5 ml) and dimethylformamide (2 drops) was heated to reflux fortwo hours and then evaporated under reduced pressure. The residue wascooled to 0° C. and treated with 0.880 aqueous ammonia; the resultingmixture was stirred at room temperature for one hour, then at 100° C.for 15 minutes, and was then cooled and filtered to give7-butylfluorenone-2-carboxamide, m.p. 185°-190° C.

The above amide (650 mg) was dissolved in dimethylformamide (11 ml) andthe solution was cooled to -20° C, stirred, and treated dropwise withthionyl chloride (1.5 ml). After stirring for a further 30 minutes at-20° C. the solution was allowed to attain room temperature over 1 hourand was then poured into ice-water (50 ml). The resulting amorphousproduct was extracted into chloroform and the chloroform solution waswashed well with water, dried over anhydrous sodium sulphate andevaporated. The residual amorphous nitrile was dissolved indimethylformamide (10 ml), treated with sodium azide (200 mg) andammonium chloride (180 mg) and heated to 110° C, with stirring, for 20hours. The mixture was poured into water (50 ml), acidified withhydrochloric acid, and the solid was filtered, washed with water anddried. Recrystallisation from ethanol gave pure5-(7-butylfluorenone-2)-tetrazole, m.p. 233°-234° C, (decomp.).

EXAMPLE 5 5-(7-Bromofluorenone-2)-tetrazole

A mixture of 7-bromofluorenone-2-carboxylic acid (850 mg), thionylchloride (5 ml) and dimethylformamide (2 drops) was heated to reflux for4 hours and then evaporated under reduced pressure. The residue wascooled to 0° C. and treated with aqueous ammonia; the mixture wasstirred at room temperature for 16 hours and at 100° C for 30 minutesand was then cooled and filtered to give7-bromofluorenone-2-carboxamide, m.p. 270°-274° C.

This amide (700 mg) was dissolved in hot dimethylformamide (11 ml) andthe solution was cooled to -20° C, stirred, and treated dropwise withthionyl chloride (1.5 ml); a yellow solid began to separate during theaddition. The mixture was stirred for a further hour at -20° C, then for3 hours at room temperature, and then poured onto ice-water (50 ml). Theyellow solid was filtered, washed well with water and dried to give7-bromofluorenone-2-carbonitrile, m.p. 205°-210° C. This nitrile (500mg) in dimethylformamide (10 ml) was treated with sodium azide (200 mg)and ammonium chloride (180 mg) and the mixture was stirred and heated to110° C. for 20 hours. The mixture was then poured into water (50 ml),acidified with hydrochloric acid, and the yellow solid was filtered,washed with water and dried to give 5-(7-bromofluorenone-2)-tetrazole,m.p. 290°-295° C. (decomp.).

EXAMPLE A Powder Capsules for Inhalation

    ______________________________________                                        Example A - Powder Capsules for Inhalation                                    ______________________________________                                        2,7-Di-(5-tetrazolyl)fluorenone                                               (0.5-7.0 μm powder) 4mg                                                    Lactose (30-90 μm powder)                                                                         46.0mg                                                 ______________________________________                                    

The powders were mixed until homogeneous and filled into suitably sizedhard gelatin capsules, 50mg of mixture per capsule.

EXAMPLE B Inhalation Aerosol

    ______________________________________                                        Example B - Inhalation Aerosol                                                ______________________________________                                        2,7-Di-(5-tetrazolyl)fluorenone                                               (0.5-7.0 μm powder)       200mg                                            Sorbitan Trioleate           100mg                                            Saccharin Sodium                                                              (0.5-7.0 μm powder)       5mg                                              Menthol                      2mg                                              Trichlorofluoromethane       4.5 g                                            Dichlorodifluoromethane                                                                              to    10.0ml                                           ______________________________________                                    

The Sorbitan Trioleate and Menthol were dissolved in theTrichlorofluoromethane. The Saccharin Sodium and diacid were dispersedin the mixture which was then transferred to a suitable aerosol canisterand the Dichlorofluoromethane injected through the valve system. Thiscomposition provides 2mg of Acid in each 100μ l. dose.

What we claim is:
 1. A method of inhibiting the symptoms of asthma orallergic rhinitis in a mammal susceptible to asthma or allergicrhinitis, which comprises administering to said mammal aprophylactically effective non toxic amount of a compound of formula (I)##STR9##wherein Z¹ and Z² are each a 5-(1-R)tetrazolyl or a 5-(2-R)tetrazolyl in which R is hydrogen or alkyl having 1 to 6 carbon atoms ora pharmaceutically acceptable salt of said compound.
 2. The method ofclaim 1 wherein the pharmaceutically acceptable salt is selected fromthe ammonium, sodium, potassium, calcium, magnesium and organic basesalt.
 3. The method of claim 1 wherein in said formula (I) Z¹ is5-tetrazolyl.
 4. The method of claim 1 wherein in said formula (I) R isalkyl having 1 to 6 carbon atoms.
 5. The method of claim 1 wherein insaid formula (I) Z² is in the 7-positioh.
 6. The method of claim 1wherein in said formula (I) Z² is in the 6-position.
 7. The method ofclaim 1 wherein the compound of formula (I) is2,7-di-(5-tetrazolyl)fluorenone or a pharmaceutically acceptable saltthereof.
 8. The method of claim 7 wherein the salt is selected from thegroup consisting of the ammonium, sodium, potassium, calcium andmagnesium salts of 2,7-di-(5-tetrazolyl)fluorenone.
 9. The method ofclaim 8 wherein the compound is 2,7-di-(5-tetrazolyl)fluorenone disodiumsalt.
 10. The method of claim 1 wherein the prophylactically effectivedose is from 2 μg to 100 mg. per kilogram bodyweight of the mammal. 11.The method of claim 1 comprising administration into the lung of themammal of a dose of from 20 μg to 0.5 mg of said compound for thetreatment or prophylaxis of allergic asthma.
 12. The method of claim 6wherein administration is effected by the oral route.
 13. The method ofclaim 12 wherein the prophylactically effective dose is from 1 to 50 mgof said compound of formula (I) per kilogram bodyweight of the mammal.14. The method of claim 1 wherein said condition is allergic asthma. 15.A method of inhibiting the symptoms of conjunctivitis in a mammalsusceptible to conjunctivitis which comprises administration to saidmammal of a prophylactically effective non-toxic amount of a compound offormula I as defined in claim
 1. 16. A method of inhibiting the symptomsof urticaria in a mammal susceptible to urticaria which comprisesadministration to said mammal of a prophylactically effective non-toxicamount of a compound of formula I as defined in claim
 1. 17. A method ofinhibiting the symptoms of eczema in a mammal susceptible to eczemawhich comprises administration to said mammal of a prophylacticallyeffective non-toxic amount of a compound of formula I as defined inclaim
 1. 18. A pharmaceutical composition suitable for administration toa mammal to inhibit the symptoms of asthma, conjunctivitis, urticaria,eczema, or allergic rhinitis which comprises a prophylacticallyeffective non-toxic amount of a compound of formula I ##STR10##whereinZ¹ and Z² are each a 5-(1-R)tetrazolyl or a 5-(2-R)tetrazolyl in which Ris hydrogen or alkyl having 1 to 6 carbon atoms or a pharmaceuticallyacceptable salt of said compound in association with a pharmaceuticallyacceptable carrier therefor.
 19. The composition of claim 18 whereinsaid tricyclic compound is in the form of a powder suitable forpulmonary administration.
 20. The composition of claim 18 in the form ofa self-propelling aerosol composition comprising said tricyclic compounddispersed in a liquid propellant in a sealed valved container.
 21. Thecomposition of claim 19 wherein said powder is incorporated in a capsulesuitable for use in an inhalation device.
 22. The composition of claim18 wherein the pharmaceutically acceptable salt is selected from theammonium, sodium, potassium, calcium, magnesium and organic base salt.23. The composition of claim 18 wherein in said formula (I) R ishydrogen.
 24. The composition of claim 18 wherein in said formula (I) Ris alkyl having 1 to 6 carbon atoms.
 25. A pharmaceutical composition asclaimed in claim 20 wherein in said formula (I) Z² is in the 7-position.26. A pharmaceutical composition as claimed in claim 18 wherein in saidformula (I) Z² is in the 6-position.
 27. A pharmaceutical composition asclaimed in claim 18 wherein the compound of formula (I) is2,7-di(5-tetrazolyl)fluorenone or a pharmaceutically acceptable saltthereof.
 28. A pharmaceutical composition as claimed in claim 22 whereinthe salt is selected from the group consisting of the ammonium, sodium,potassium, calcium and magnesium salts of 2,7-di-(5-tetrazolyl)fluorenone.
 29. A pharmaceutical composition as claimed in claim 23wherein the compound is 2,7-di-(5-tetrazolyl)fluorenone disodium salt.30. A pharmaceutical composition as claimed in claim 18 wherein thecomposition is in the form of a discrete dosage unit selected from atablet, capsule, lozenge and sachet, each unit containing from 50 to 500mg. of said tricyclic compound.